Gas cupola furnace

ABSTRACT

A gas cupola furnace comprises a shaft, having at the bottom thereof, a hearth in which molten metal is superheated by introduction of a combusted gaseous fuel into a tunnel which leads to the hearth, the molten metal having various reagents added thereto by means of channels which lead to the molten metal which channels may be disposed in the walls of the shaft or the walls of the hearth.

PATENIEU FEB '2mn f'lllZ FILI GAS CUPOLA FURNACE The present invention relates to the field of metallurgy. and more particularly to methods of melting metals and to gas cupola furnaces for effecting the same.

Known in the prior art is a gas cupola furnace constructed according to the Soviet Authors Certificate No. l67.ol 3. Class 3 la l/Ol. The shaft of this cupola furnace is provided with two shoulders: the lower for maintaining the column of the charge materials and the upper one for preventing the charge from falling into the lower part of the cupola furnace, being essentially a chamber for superheating the molten metalA The melting and superheating of the metal are carried out in the cupola furnace shaft when firing a gaseous fuel in its lower part. This cupola furnace is suitable for providing molten metal heated to a temperature sufficient for casting thinwalled parts. The production capacity of the gas cupola furnace is thereby higher than that of a coke cupola furnace of the same dimensions. while it is simpler as to its design and occupies a smaller floor area.

ln the process of melting metal in this cupola furnace, however. it is impossible to control the chemical composition of the metal produced` to effect the operations of refining. modifying` alloying. deoxidizing` eliminating the harmful impurities from the molten metal. and adding to it useful constituents. All these operations are carried into effect outside the cupola furnace` which necessitates the use of additional equipment and a decrease in the metal temperature.

An object of the present invention is to eliminate the abovementioned disadvantages. Other objects and advantages of the invention will become more fully apparent from a consideration of the following description thereof.

The principal object of the invention is to provide a method of making metal in a gas cupola furnace, enabling control of the chemical composition of the metal by carrying out the operations of modifying, alloying, refining` and deoxidizing thc molten metal, eliminating the harmful impurities thereof and adding to it useful constituents without a decrease in the temperature of the metal thus produced. as well as to provide a gas cupola furnace which is suitable for effecting the introduction of the above-mentioned reagents into the liquid metal to be superheated in the cupola furnace.

This object is accomplished by the provision ofa method of making metal in a gas cupola furnace, comprising superheating the molten metal; and directly introducing into the molten metal the reagents capable of varying the chemical composition of metal. Said reagents can be added to the metal by blowing them therethrough. The reagents can be introduced into a gaseous carrier, and thus they may be blown into the molten metal or brought on the surface of the metal bath, pro` vided that there exists a contact between the gaseous carrier andthe molten metal.

lt is expedient to preheat the reagents before their addition into the molten metal to be superheated in the cupola furnace.

Hydrocarbons` which are employed as a reagent. may be heated up to a temperature at which the cracking process starts, and thereafter they are to be added to the molten metal superheated in the cupola furnace. lt is expedient to add the reagents. contributing to the formation of graphite of spheroidal shape in the metal for instance` magnesium vapors, into the molten metal which is to be superheated in the cupola furnace.

The method is carried into effect in a gas cupola furnace, provided with channels` adapted for supplying said reagents into the molten metal to be superheated in the cupola furnace. said channels communicating with the vessel intended for the reagents and with the cavity ofthe superheating chamber. The channels intended to supply the reagents into the molten metal which is to be superheated in the cupola furnace, may be provided in the walls or in the walls and hearth ofthe superheating chamber, The vessels with the reagents may be connected to a tuyere or a tunnel for burning the gaseous fuel.

The details of the present invention will become more fully apparent from a consideration -of the following description of an exemplary embodiment of the method of making metal in the gas cupola furnace and an embodiment of the gas cupola furnace according to the invention. taken in conjunction with the accompanying drawings. in which:

FIG. l is a longitudinal section of the gas cupola furnace` according to the present invention; and

FlG. 2 shows the same cupola furnace. in a cross-sectional view taken along the line ll-ll of FIG. l.

The gas cupola furnace is provided with a lower shoulder l (FIG. l) intended to maintain the column of charge materials and an upper shoulder 2 intended to prevent the charge from falling into the lower part of the cupola furnace shaft, i.e. the chamber for superheating the molten metal. Disposed in the shaft of the cupola furnace, the shoulders are provided with channels 3 and 4 to allow a coolant (water) to pass therethrough. The bottom part of the shaft is provided with a hearth 5, made witha depression in the form of a well 6 to be filled with molten metal. ln the lower part of the superheating chamber, there is provided a forehearth 7 (FIG. 2) having a tunnel 8 for directing the combustible mixture. which is to be burned therein, into the superheating chamber on the surface of the molten metal which is in the hearth well. A tuyere 9 is attached to the forehearth end. The hearth of the cupola furnace is provided with channels l0 terminating in the well. The channels are adapted for supplying reagents into the molten metal, ensuring the making of metal of the specified chemical composition. Provided in the shaft lining arc channels ll. preferably in the form of pipes intended for heating the reagents prior to their addition into the molten metal. Connected to the tuyere 9 is a hopper l2 for the powdered additives that are supplied into the gas-air combustible mixture through a channel 13. A second hopper may be connected by means of a channel 14 with the forehearth tunnel.

In another exemplary embodiment, a hopper or batcher l5 is connected by means of a channel 16 to the well of the molten metal on the cupola hearth.

The gas cupola furnace operates in the following manner. A charge, consisting of metal and fluxes` is charged into the shaft of the cupola furnace. Gas and air are supplied into the tuyeres, and their mixing is thereby effected. The gas-air mixture thus obtained is burned in the tunnel. and. on arriving into the shaft` the mixture is caused to rise upwards to the charge, which thereby commences to be melted and to flow down from the lower shoulder in droplets into the hearth well. The surface 0f metal in the well is continuously cleaned of slag which flows through a tap hole 17 into a reservoir 18, The molten metal is superheated both at the surface cleaned of the slag and during the blowing therethrough ofthe products of combustion and preheated reagents supplied through the channels provided in the hearth.

The molten metal in the well is blown through a plurality of channels by a mixture composed of a gas and powdered additions that are supplied from the hopper or batcher l5. The gas is employed to handle both the powdered and liquid materials that are, if necessary, supplied thereinto from the corresponding vessels. When passing through channels provided in the shaft walls, hydrocarbons are subjected to cracking, while other reagents are preheated which favorably affects the process of making metal. The reagents that are blown through the molten metal thus enable removal of the harmful impurities from the metal and introduction therein of the useful con stituents. The bubbling of the molten metal occurs thereby in the well. and the luminosity of the flame is increased in the superheating chamber, which contributes to an increase in the temperature of the molten metal. The process of treating the molten metal to be superheated is carried out in a continuous manner, as a result of which in the cupola furnace there are effected the operations of carburization, modification. alloying, removal of sulfur, and from the metal, an increase in the content of silicon. manganese and other useful constituents. There appears the possibility to remove carbon when processing iron into steel, to deoxidize the metal` to remove the slag inclusions and to carry into effect continuously or periodically the complex metallurgical processes. The metal is carburized by blowing through it graphite, calcium carbide or other carbonaceous materials. To remove sulfur from the metal. it is to be blown through by matter containing calcium` magnesium, manganese and other substances contributing to the transfer of sulfur into the slag. The operations of deoxidizing. modifying and saturating iron u ith silicon are effected by blowing ferrosilicium and silicocalcium thereinto, while the metal may be cleaned from nonmetallic inclusions by blowing thereinto the fluoric and chloric salts of barium and calcium.

Employed as a gas carrier is an inert or natural gas which is to be blown through the molten metal. Preheated when passing through channels ll the gas arrives in the metal along the channels l0. To increase the content of carbon in the metal and to deoxidize it calls for blowing hydrocarbons through the molten metal. When the metal is blown through by pure oxygen` its temperature is increased, while the contents of carbon, silicon and manganese are decreased. The molten metal may be blown through by a gas-oxygen or a gasair mixture. or any other deoxidizers.

To allow the corresponding chemical processes to occur, the powdered additions, for example, fluxes, modifiers and other reagents, are to be introduced into the gas-air mixture prior to its arrival in the tunnel or during this operation. The introduction into the tuyere flame of the powdered reagents is likely to increase the luminosity of the flame and their area of contact with the metal` and hence their efficiency of utilization.

The reagents, such as vapors or dust of magnesium forming in the metal (iron) graphite of spheroidal shape, are to be blown through the molten metal in the well, which enables manufacture of a high-resistance iron. This reagent may be introduced both through the channels l and ll, and through channels 16.

Though the present invention is described in' connection with a preferable embodiment, it is evident that there maybe allowed modifications and variants that do not depart fromthe scope and concept of the invention, as will be readily understood by those skilled in the art.

We claim:

l. A gas cupola furnace adapted for containing superheated molted metal therein, said furnace comprising a shaft with a lining, a shoulder disposed in the median part of said shaft for maintaining a column of charge materials thereabove and form a preheating chamber, a second shoulder disposed above said first shoulder for preventing the charge from falling into the lower part of the shaft which constitutes a superheating chamber, a hearth provided with a depression in the form of a well, said hearth being disposed in the lower part of said superheating chamber, a forehearth proximate the lower part of said shaft, at least one tunnel in said forehearth for burning gaseous fuel therein, said tunnel leading to said superheating chamber, a tuyere connected to said tunnel, and channels extending directly into said well for supplying reagents into the molten metal to be superheated therein, and at least one reagent vessel communicating with said channels to supply reagent thereto and to said molten metal, said channels extending longitudinally in the shaft lining whereby the reagents are preheated prior to introduction into said well.

2. A gas cupola furnace according to claim 1, wherein said channels are also disposed in the hearth.

3. A gas cupola furnace according to claim 1 comprising a further reagent vessel connected to said tuyere.

4. A gas cupola furnace according to claim l comprising a further reagent vessel connected to said tunnel for the combastion of gas. 

1. A gas cupola furnace adapted for containing superheated molted metal therein, said furnace comprising a shaft with a lining, a shoulder disposed in the median part of said shaft for maintaining a column of charge materials thereabove and form a preheating chamber, a second shoulder disposed above said first shoulder for preventing the charge from falling into the lower part of the shaft which constitutes a superheating chamber, a hearth provided with a depression in the form of a well, said hearth being disposed in the lower part of said superheating chamber, a forehearth proximate the lower part of said shaft, at least one tunnel in said forehearth for burning gaseous fuel therein, said tunnel leading to said superheating chamber, a tuyere connected to said tunnel, and channels extending directly into said well for supplying reagents into the molten metal to be superheated therein, and at least one reagent vessel communicating with said channels to supply reagent thereto and to said molten metal, said channels extending longitudinally in the shaft lining whereby the reagents are preheated prior to introduction into said well.
 2. A gas cupola furnace according to claim 1, wherein said channels are also disposed in the hearth.
 3. A gas cupola furnace according to claim 1 comprising a further reagent vessel connected to said tuyere.
 4. A gas cupola furnace according to claim 1 comprising a further reagent vessel connected to said tunnel for the combustion of gas. 